This invention relates to an oven structure and associated method of cooking especially designed for mass cooking of food products. More particularly, the invention is directed to an oven construction and cooking method for large production cooking wherein the food products are continuously transported in a spiral vertically ascending path through a cooking chamber to effect slow thorough cooking of the food products.
A self-supporting spiral conveyor is known in the prior art as shown in U.S. Pat. No. 3,938,651 issued Feb. 17, 1976. The spiral conveyor system shown in this patent is adapted for use in a freezer structure which is specially designed to fast-freeze mass quantities of food products. The conveyor belt is arranged to follow a path consisting of a number of superimposed, helically extending tiers wherein links on either side of the conveyor belt support the tiers on top of one another to provide a self-supporting conveyor belt system. The conveying device is stated to be useable to convey food items through a confined space for a certain dwell time for treatment of the food products.
For mass cooking of food product such as in industrial cooking operations, other oven structures are known to include a conveyor means which are formed in a spiral path for continuously conveying food product through a cooking chamber. In U.S. Pat. No. 4,582,047 a high humidity steam oven includes a continuously running conveyor means having a spiral conveyor path wherein a steam atmosphere is provided in the cooking chamber from two separate steam sources. An internal source comprising a pool of water disposed on the floor of the cooking chamber is heated to produce steam therefrom. The oven construction also includes an internal sanitation system for cleaning of the cooking chamber.
A similar oven construction is shown in U.S. Pat. No. 4,363,263 which shows the use of the oven in conjunction with a chilling chamber as another treatment for the food products passing therethrough. In addition, a similar spiral conveyor path is formed in a high humidity chilling system as shown in U.S. Pat. No. 4,319,460.
Another cooking oven is shown in U.S. Pat. No. 4,737,373 which is directed to a method of cooking food products on a continuous feed basis wherein slow cooking of the food product and browning of the food product are achieved in separate systems. The slow cooking system comprises an oven having a continuous conveyor formed in a straight or spiral path having a cooking chamber with a steam environment in which the food products are conveyed. After thorough cooking, the foods products are directed to a browning oven wherein impingement of heated air produces surface effects as desired. A heat exchanger/boiler is provided wherein heat from the browning oven is exchanged with water to produce steam which is used in the slow cooking oven.
In all of the cooking ovens which are used for mass production of cooked food products and having a spiral conveyance path within a cooking chamber, there have been found to be associated problems with cooking efficiency, output of the oven, adaptability to a variety of food products, the inability to achieve various surface treatments of the food products, cleanability as well as other problems. The ability for food products to be cooked thoroughly while keeping dwell time in the cooking chamber of the oven to a minimum for adequate output from the oven is inhibited to some degree by the conveyor means utilized in these prior ovens. The conveyor systems have normally included a spiral supporting path on which an endless conveyor belt is supported and transported by suitable conveyor driving means. Steam heat utilized in the cooking chamber of the oven is merely introduced into the cooking chamber and is not effectively circulated within the cooking chamber.
Thus, in these prior oven systems, efficient and effective heat transfer in the cooking chamber is inhibited by non-circulation of the cooking medium and the consumption of energy to heat the conveyor belt's supporting structure may be significant. Additionally, although some cleaning systems have been provided in the prior art cooking ovens, a problem still exists in that the structure of these ovens require extensive and thorough cleaning of all interior surfaces of the cooking chamber including the conveyor belt supporting structure which may not be able to be achieved efficiently and quickly to maintain cost effective production of cooked food products. It is additionally found that the prior art systems have no means for obtaining surface treatment of the food products as they pass through the cooking chamber of the oven and have resorted to separate equipment to provide surface treatments such as browning, crisping, or other desirable features.